Often, fasteners used to assemble performance critical components require tightening to a specified torque level. A popular method of tightening such fasteners is through the use of a torque wrench. The accuracy and reliability of these wrenches is important to insuring that the fasteners are properly tightened the specified torque levels.
Torque wrenches vary from simple mechanical types to sophisticated electronic types. Mechanical type torque wrenches are generally less expensive than electronic ones. There are two common types of mechanical torque wrenches, beam and clicker types. With beam type torque wrenches, a beam bends relative to a non-deflecting beam in response to the torque applied. The amount of deflection of the bending beam relative to the stationary beam is indicative of the torque applied. Clicker type torque wrenches work by pre-loading a snap mechanism with a spring to release at a specified torque, thereby generating a click noise.
Electronic torque wrenches (ETW) tend to be more expensive than mechanical torque wrenches, and more accurate as well. Often, ETWs allow a user to preset a torque limit, store data for later retrieval by the user, and alert the user when the torque limit is reached. ETW models range from relatively low-cost basic models to expensive models with multiple features.
Regardless of which type ETW is used, torque extensions may be required to tighten fasteners that are in locations that the torque wrench will not reach. One of the most common methods of attaching a torque extension to an ETW is to replace the original drive head with an extension that has its own drive head. Once the extension is inserted, the readings of the ETW must usually be corrected for any change in lever arm length due to the extension. With the extension in place, the actual torque experienced by the fastener will be either higher or lower than what is actually displayed on the ETW, depending on whether the extension extends outwardly or inwardly from the end of the ETW, respectively.
For each different length extension, a different correction factor must be calculated. Typically, the end user calculates a correction factor and either divides or multiplies the desired final actual torque value to be applied to the fastener by this correction factor to determine the final compensated set torque value (as displayed by the ETW) that is to be input into the ETW. Whether the actual torque value is divided by or multiplied by the correction factor is dependent upon the method of determining the correction factor. The final compensated set torque value is the value at which, when displayed, the user ceases to apply torque to the fastener. Typically, the user will only know the final compensated set torque value accurately and is not able to accurately determine the intermediate torque values. In other words, the user only calculates the final compensated set torque value for the set torque and will not be able to continuously monitor the actual torque values during torquing operations as only “compensated” values are displayed by the ETW. This situation can lead to over and under-torquing, possibly resulting in loss of performance of the fasteners.
The present invention recognizes and addresses the foregoing considerations, and others, of prior art constructions and methods.